Check out for ESFM emulation

[Wohlstand]

ESFM is an extended clone of OPL3. Recently I got the ESS card with ES1688F chip that has ESFM. I tried it in action with my old Windows 98 machine, and it's very interesting thing. I heard about ESFM before from @jpcima, however, I had't much information about it and how it actually sounds. So, getting the real ESS card with a compatible chip gave me some proveground for researches.

ESS Technology's in-house developed derivative, termed ESFM, is an enhanced, 20-voice, 72-operator, OPL3-compatible clone incorporating two operating modes, a Native mode and a Legacy mode, which controls its feature-set and behavior. In Native mode, ESFM allows more than six 4-operator FM voices to be mapped, potentially allowing for a significant increase in the complexity of tones generated. The drivers for Windows 9x incorporate their own custom instrument patches which make use of this extended mode. Conversely, Legacy mode provides full backward-compatibility with Yamaha's YMF262. ESFM's output in this mode is moderately faithful to the YMF262 overall, but some tones are rendered quite differently, resulting in unique distortions in the sound and music of some games.

However, I saw nothing about any sort of emulation of this chip. However, there are some details at VOGONS: https://www.vogons.org/viewtopic.php?f=46&t=37497&start=120#p738552 (thanks to @nukeykt for a hint)

[freq-mod]

Yeah, interesting card. In its nativ mode, it reportedly has 18 4-op channels (18x4=72). But it's not a dual OPL3, so 2-op channels count stays the same.

Reverse enginnering project: https://github.com/pachuco/ESSPlayMid

[pachuco]

https://github.com/pachuco/Buttler I'm working on separate project of providing hardware read/write port access to other people online, so people can remotely play with other people's hardware. Which is totes not a reckless and dangerous thing to do. I'll lend my ESSFM for study on request.

Currently not finished, so stay tuned, I guess.

[sneakernets]

This is a great idea. I would love to write/extend DMXOPL3 to support this if there are more features.